One of the problems of widely available rotary viscometers is that of temperature drift. For example, the Brookfield Engineering Laboratories, Inc., (BEL) model CAP3000™ cone and plate rotary viscometer with a MSI brand variable inductance transducer has a temperature drift of about −/+2% full scope error over about a −10 to 50° C. range of angular deflection. Coping with axial movement due to e.g. cone tip wear is also an issue in maintaining reliable readings over long durations of instrument use. It is also a need to enable a large angular range for full scale.
There is also a need for continuous reading of viscosity. For instance, some BEL cone and plate viscometers use an optical time base sensing mechanism for angular air placement giving a limited number of readings per revolution (e.g. two) at 0.01 rpm.
It is an object of the invention to provide a greater precision in such viscometer. It is a further object to reduce or eliminate problems arising out of axial orientation issues and/or temperature variations. It is a further object to achieve the foregoing with minimal change to configuration of the viscometer and its electrical circuitry and computer interfacing.